An only dog has not been waiting for a companion; he has been enjoying a complete life in which every walk, sofa corner, and human hand was his. A puppy changes the arithmetic of all three at once, and the resident dog's cooperation depends on how little of his good life the newcomer appears to cost him. Plan the introduction as a merger negotiated in his favour: first meetings away from home, resources separated before they can be argued over, and retreat rights that are enforced by the humans rather than left for him to defend himself.
First Meetings and the Parallel Walk
Meet on neutral ground, a quiet street or park neither dog owns, with two handlers and two leads. Walk in parallel at a distance where both dogs can notice each other and still look away, eat treats, and walk loosely, closing the gap gradually across the walk and across several walks if the first stays tense. Let brief, voluntary sniffing happen when bodies are loose and curved rather than face-on and still, then call both dogs away cheerfully and keep moving; movement defuses social pressure that standing introductions accumulate.
Bring the puppy home while he is settled in another room, and let the puppy explore a limited area while he observes from behind a gate with something rewarding to do. First home contact should be short, in the garden or largest room, with leads trailing and exits open so either dog can disengage. End while things are still going well. A boring first day is a triumph; a puppy played with until frantic will pester an older dog in ways that sour first impressions.
Separate Resources, Protected Retreats
Feed in separate spaces with a door or gate between, and keep that arrangement long after the dogs seem friendly, because food guarding can appear weeks in, usually around the resource that matters most. Beds, chews, and resting places follow the same rule: his bed is his, placed where the puppy cannot bounce onto it, and the puppy's bed lives elsewhere. Lift high-value toys and long-lasting chews during shared time at first, returning them for solo sessions, since a treasured object on the floor converts a peaceful room into a negotiation neither dog should have to conduct.
Guarantee him puppy-free time every day, behind a gate or in his favourite room, plus unchanged one-to-one time with you: his usual walk, sometimes without the puppy, his training games, and his evening routine intact. Puppies need the mirror-image lesson, learning to settle behind a gate with a chew while life happens elsewhere, because a puppy who can only rest in company becomes a demanding adult. Separate the dogs whenever nobody is actively supervising, and overnight, until the relationship has months of evidence behind it rather than a good first week.
Attention, Friction Points, and the Settling Timeline
Divide attention deliberately rather than apologising for the puppy all day. Greet him first sometimes, train the puppy in another room often, and give one person the watching job during shared time while another manages the puppy. The predictable friction points are narrow doorways, the sofa, food preparation areas, and your lap; manage them with gates and turn-taking instead of waiting for a snap to establish policy. A growl from him is information, not wickedness: remove the puppy, and adjust the setup so he needs to say it less often.
Progress usually looks undramatic: parallel rest in the same room, voluntary proximity on walks, relaxed ignoring of each other's beds and bowls. Some older dogs take weeks to grant even that, and a slow timeline with good management is a success. Seek a qualified behaviour professional promptly if you see guarding that escalates, pinned or chased behaviour the puppy cannot escape, or stress in either dog that management is not reducing. Two dogs means two profiles, two routines, and twice the scope for mixed messages, so KinsLe helps by holding both dogs' feeding, retreat, and training notes where the family can share them through Family Sharing and keep the household rules identical whoever is on duty.